Book Review - ‘Stealing Speed’

Stealing Speed: "The Biggest Spy Scandal in Motorcycle History" by Mat Oxley

is a compelling true story of Cold War espionage, innovation, and betrayal in the world of motorcycle racing. The book follows Ernst Degner, an East German Grand Prix rider who risked everything to defect to the West in 1961. In doing so, he smuggled the revolutionary two-stroke engine technology developed by MZ’s chief engineer, Walter Kaaden—technology that would soon propel Suzuki to dominance in world racing.

Oxley expertly weaves together the technical brilliance of Kaaden:

“Kaaden was certainly the first man to put such theories into practice. He was convinced that the sound waves moving through a two-stroke exhaust could be harnessed in the same way they had been used in the V-1 to create more horsepower. He invented weird, bulbous exhaust systems that he believed would control and exploit the pressure waves emanating from the combustion chamber.

And these bizarre-looking devices did exactly that, at the same time adding a sharp, purposeful crack to the exhaust note. 'The first time I got the exhaust correct, I found a lot of power,' he said, recalling that magic day. Suddenly, as if from nowhere, he had found 20 percent more horsepower.

The expansion chamber exhaust system did for the two-stroke's exhaust phase what the rotary valve did for the inlet phase, using one pressure wave to lock unburned gases in the cylinder, then the opposite pressure wave to suck the burned gases out of the combustion chamber more quickly and more efficiently. By harnessing the gas resonances, he had effectively supercharged the engine by the backdoor—for free.

The expansion chamber was undoubtedly Kaaden's greatest achievement. The physics he had learned during the war revolutionised two-stroke performance and is still applied today when any expansion chamber is designed.”

A crop of early expansion chambers

Oxley also writes vividly about the oppressive reality of life behind the Iron Curtain, and the high-stakes world of Grand Prix competition.

“At the TT, Hocking and Hailwood were leading the Junior race, pushing hard. Tom was riding on the outer limits on his Honda, trying to stay with the more stable MVs of Hocking and Hailwood, when he crashed at Laurel Bank and killed himself. Gary came in and said, ‘There you are, I told you it was going to happen. I killed Tom today.’”

Hocking, who had been a close friend of Phillis, was so upset that he quit bikes and moved into car racing. Ironically, he died testing a Formula One car later that same year.

Racing car drivers were also dying at a horrific rate, even though they enjoyed somewhat more protection than motorcycle racers. The protective clothing for bike racers at the time was desperately rudimentary. On his head, the rider wore a pudding-basin helmet—or "battle bowler"—a lacquered canvas or papier-mâché shell with a cork liner, and goggles.

These helmets, perched loosely atop the rider’s head, offered minimal protection—sometimes none at all—as they were prone to flying off in accidents or shattering into pieces. In such moments, the rider’s skull could crumple like the shell of a hard-boiled egg.

The Biggles-style goggles weren’t much better. 1960s factory Honda and Yamaha rider Tommy Robb recalls headbutting a seagull at the TT, as he came into Ramsey at about 130 mph:

“I made the mistake of coming up from behind the screen, so I could see exactly what it was up to, but the thing hit me,” he says. “It was like being hit by Muhammad Ali. The left goggle glass disintegrated and the steel rim flattened against my face. I was covered in blood, gore, and feathers. I limped back over the Mountain. My wife was worried I’d had a crash. I told her I’d hit a seagull, and she said, ‘Oh, the poor thing.’”

Kaaden rides through the Sachsenring’s cobbled final turn 1951

Degner’s daring escape from East Germany—timed perfectly with the Swedish GP—reads like a spy thriller, but it’s all fact. His actions not only changed the course of his own life, but also shifted the balance of power in international motorsport.

With his experience as an Isle of Man TT winner and motorsport journalist, Mat Oxley brings both technical clarity and narrative pace to the story. He captures the emotional and political tension of the era while explaining complex engine dynamics in a way that’s both accessible and engaging.

Stealing Speed is a must-read for vintage motorcycle lovers, racing enthusiasts, and history buffs alike.

ISBN: 9781844259755 — First published in 2009 by Haynes Publishing.